Yesterday out on the Twenty Mile River, I reveled in watching silver salmon hanging the shallow water mere inches beneath the surface, marveled at the bald eagles nesting high above the wetlands and nodded in awe as Kevin, our fishing guide, pointed out the huge trees along the riverbanks gnawed by beavers. (Once he brought them to our attention, we realized they were everywhere -- spaced out along the riverbank every 50 feet or so.)

I had no idea what I was really looking at, until an Aleut wise man explained it tonight at dinner.

Larry Merculieff is co-founder and former chair of the Alaska Indigenous Council on Marine Mammals among other groups. He was raised on St. Paul, one of the Pribilof Islands southwest off the Alaskan mainland, where the Aleut seal hunters have lived for more than 10,000 years.

The average Alaskan -- native and nonnative alike -- eats 420 pounds of wild food per year, he said, more than anywhere else in the U.S.

"That means we have to maintain a profound and intimate relationship with our environment," said Merculieff. Like the climate scientists, what disturbs Merculieff most isn't just the simple fact of change itself. It's the speed at which it is occurring.

Elizabeth ShawLarry Merculieff, an Aleut from St. Paul Island

As the snow pack lessens and the glaciers recede, inland water levels are dropping dramatically.

"We're seeing salmon with lesions on their bodies caused by scraping their bodies on the rocks," he said. The fish are being attacked by parasites that previously could not live in the region's cold waters. But the rising air temperatures and lower water levels are warming the waters to the point where that's no longer true.

At the same time, beaver populations are mushrooming, following the northern spread of tree species that once could not thrive so near the Arctic circle. They are now along every major Alaskan river, he said, building dams and blocking waterways that exacerbate the problem. Beaver urine is also bad for salmon eggs, he said. The salmon population is being stressed by factors more critical and complex than those of 50 years ago.

Elizabeth ShawTwo trees being felled by beaver along the Twenty Mile River.

"Our elders predict the salmon will disappear within the next 10 years," he said. But it isn't just the salmon. The sea lion population has dropped 80 percent in the last 30 years. Otters are down 70 percent. The snow crab are virtually gone from the Bering Sea. Native hunters are finding seal in walrus stomachs instead of mussels and clams. Polar bears are floating dead in the water, stranded on ice floes too far from shore.

Humans are endangered too. As the sea ice diminishes, coastal flooding is destroying native villages. In 2004, 34 villages were flooded out. Five on the frontline must move within the next few years at a cost of millions of dollars. The loss of hunting -- the main conduit of tradition connecting one generation to the next -- is destroying indigenous cultures. An estimated 70 percent of the young native men ages 17-27 have been lost to suicide, alcoholism or prison. He is the last generation of his people to be raised fully in the Aleut traditions.

"It's possible within the next two generations the Alaskan natives as distinct cultures probably won't be here."

I think about being out on the Twenty Mile River yesterday, watching the sun rise above the mountains and hooting with excitement at reeling in my first silver salmon. And now I worry: will it also be my last?.